9th ECAC – Special issue

Wibig, J.; Fortuniak, K.; Przybylak, R.

Meteorologische Zeitschrift Vol. 22 No. 5 (2013), p. 531 - 532

published: Oct 1, 2013

DOI: 10.1127/0941-2948/2013/0547

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This special issue introduces a number of studies presented at the 9th European Conference on Applied Climatology by teams consisting mainly of Polish researchers. The papers presented here illustrate the diversity of climate research conducted in Poland.
Climate change issues are now among the most important environmental problems. Regardless of their reasons, be it natural or anthropogenic, they can cause significant changes in frequency and/or intensity of extreme weather and climate events. Therefore, they can exert a strong impact on human life, ecosystems and economy. So it is not surprising that there is a growing interest to address this aspect of climate changes. Four from the ten papers included concern the occurrence of extreme events in the context of atmospheric circulation (POREBSKA and ZDUNEK, 2013; ZMUDZKA, 2013; USTRNUL et al., 2013; PIANKO-KLUCZYN´ SKA, 2013). The first paper from this series presents the occurrence of cold and heat waves in relation to high pressure blocking situations (POREBSKA and ZDUNEK, 2013). The heat and cold waves were distinguished for 30 stations located in Central Europe based on the daily maximum temperature records. The high pressure blocking detection algorithm was adopted from SCHALGE et al. (2011) and the blocking situations were classified according to the high pressure system position with respect to Central Europe. It was shown that cold and heat waves were often associated with the occurrence of blocking situations over the Atlantic Ocean and Eastern Europe, respectively. The blocking situations lasting 5 days or longer coincided with extreme thermal events more often than the shorter ones.
In the second paper, which concerns weather extremes, the extreme thermal resources in Poland during the growing season are compared with the circulation patterns (_ZMUDZKA, 2013). The calendar of circulation patterns developed by LITYN´ SKI (1969) was used. This calendar is based on zonal and meridional components of geostrophic wind and air pressure in Warsaw. The extreme thermal resources were defined on the ground of 10th and 90th percentiles of effective accumulated temperatures in the growing season and in the period of active plant growth. A significant increase in thermal resources was shown, both in the length of these periods and in the growth of the temperature surplus over thresholds. The occurrence of extreme thermal resources is determined by the average frequency of advection from the South. The pressure system influences the effective accumulated temperatures during the period of the active plant growth.
The impact of circulation on the extremes is also evaluated in the third paper in this issue (USTRNUL et al., 2013). Here the composite circulation index (CIE) of weather extremes is introduced as a mean of the conditional probabilities of the occurrence of extremes for particular types. The CIE was validated using the Pearson correlation coefficient measuring relationships between the extreme values (Tmax, Tmin, RR) and the values of the partial indices (PIE), probability of detection, Bayes conditional probability and false alarm ratio. The paper confirms the significance of atmospheric circulation in the formation of temperature and precipitation extremes in Poland. The aim of the next paper is to verify the hypothesis that there is a connection between the drought occurrence and intensity and the state of the stratosphere defined by temperature, geopotential height and zonal wind component at constant pressure surfaces from 250 to 10 hPa (PIANKO-KLUCZYNSKA, 2013). The paper uses self-organizing maps and fuzzy classifications for the determination of the input stratospheric patterns and the reconstruction of drought classes. It is shown that the method is promising, however, the validation of the model parametrization should be carried out separately for each station. In the paper by PIOTROWSKI and JEDRUSZKIEWICZ (2013), the projection of future temperature changes is considered in relation to projected changes in the circulation patterns. On the basis of the selected regional climate models, changes in the frequencies of the atmospheric circulation types in winter between the scenario period 2021–2050 and the reference period 1971–2000 were examined. Circulation types characterized by relatively high positive temperature deviations of mean winter temperature in the future scenarios were distinguished, as well as those characterized by negative temperature deviations. It was shown that the projected future changes in temperature are related to the projected changes in frequency of circulation patterns.
The main objective of the paper by SZYMANOWSKI et al. (2013) is to develop a procedure for the creation of air temperature fields in Poland that could be applied to the air temperature data aggregated on different time scales from daily to annual averages. Geographically Weighted Regression – Kriging algorithm, based on Geographically Weighted Regression (GWR), was applied. It was shown that the spatial field of temperature is better fitted by local models, so the local GWR method works better than the global Multiple Linear Regression. Because of spatial autocorrelation in the residuals, the application of ordinary kriging of residuals often improves the results.
The next two papers explore the possibility of using theWeather Research and Forecasting Model (WRF) for modelling local scale phenomena. CZERNECKI (2013) presents an attempt to create wind speed time series in the southern part of the Baltic Sea using 2-way nesting with horizontal resolutions of 27 and 9 km. It was shown that the spatiotemporal structure of wind fields was reconstructed quite well, however, the model underestimated the wind speed in offshore areas and overestimated it in onshore areas. KRYZA et al. (2013) are trying to provide a quantitative precipitation forecast at high spatial (10 km · 10 km and 2 km · 2 km) and temporal (1 hour) resolutions. Their model was run with two parametrizations of convection (Kain-Fritsch and explicitly resolved deep convection). The evaluation of forecasts was made for the area of SW Poland and the period between 3rd March 2012 and 18th June 2012. It was shown that Kain Fritsch based runs have higher probability of detection and explicitly resolved deep convection runs have higher values of success ratio. However, none of the configurations tested was able to resolve a highly local episode of intensive rainfall observed in the vicinity of Wrocław on 3rd May 2012.
The paper of ZIELIN´ SKI et al. (2013) demonstrates the possibility of application of scintillometry in urban areas. The results of turbulent sensible flux measurements with a large aperture scintillometer (LAS) in Ło´dz´ in Central Poland are described and compared with the data obtained from two eddy covariance towers (EC) located in the eastern and western part of the city centre. A strong agreement between these two methods of sensible heat flux assessment was shown, however, discrepancies were found when the characteristics of source areas differed significantly. It was shown that the scintillometer measurements could be a reliable source of information on the exchange of heat between the surface and the overlying air in the urban boundary layer. The last paper of this issue characterises the bioclimatic conditions in Szczecin (NIDZGORSKA-LENCEWICZ and MAKOSZA, 2013). The Universal Thermal Climate Index (UTCI) and the Effective Temperature index (ET) were used to assess the heat stress of humans. It was shown that on the yearly scale the most favourable conditions occur in the city centre and the southern districts. The thermal stress is more often connected with cold than heat. Heat related discomfort is more often observed in the city centre and the cold related discomfort is more frequent in the outskirts.
The relationship is shown between biothermal sensation and the level of ozone (O3) as well as the particulate matter (PM2.5) concentration. The Guest Editors of this Special issue wish to thank the contributors, the reviewers and the publishers. References